Have Sundays always been completely reliant on overtime workers, or was there a time (in the recent past) when people were rostered to work on Sundays?
The whole National railway system in
BR▸ days was reliant on overtime to cover not only Sundays but the Monday to Saturday roster; yes railway workers were on a 6 day roster.
Even today
NR» maintenance and operations rely on quit heavily overtime to cover shortage of staff in key areas this becomes very acute at holiday peak times of the year. Some of the maintenance gaps are covered by contractors but they are very expensive in the long term and the contractors call out rates are eye watering.
The whole industry suffers from skilled staff, difficult to recruit when the rates of pay and working hours / conditions are more favourable in other industries